Advances in nano/microfabrication technology have led to the deployment of smaller, faster, and more efficient portable, wireless, and autonomous devices. Today's devices have significantly improved multitasking and computing capabilities that lead to increased energy requirements. These devices currently rely on secondary batteries like the Ni—Cd, Li-ion, and Li-polymers as power sources, but the need for constant replacement and recharging, interrupted operation, disposal issues, and increasing power requirements has prompted the development of alternative power sources like polymer electrolyte fuel cells as replacements.
Conventional polymer electrolyte membrane (PEM) fuel cells find application as power sources for stationary and portable systems. For portable applications, they are marketed as replacements for secondary (rechargeable) batteries which are currently limited for use by their need for constant replacement and recharging, interrupted operation, disposal issues, and inadequate power density for today's sophisticated devices. Fuel cells are high energy power sources that produce direct-current (“DC”) electricity directly from the stored chemical energy in their fuel and oxidant inputs. Such inputs are external to the power generation device. A conventional ion-conducting polymer electrolyte membrane (PEM) micro fuel cell is a sandwich-like stack of separate layers that facilitate electronic, protonic, and fluidic transport. Nafion® membranes (DuPont Corp., Wilmington, Del.), for example, are commonly used because of their proton-conducting properties.
In conventional PEM micro fuel cells, the auxiliary layers that serve as flow field, current collectors, and reactant distributors contribute significantly to the size and weight of the device, leading to bulkier devices and consequently reduced power density on a volumetric and mass basis. Moreover, the fabrication of such devices is complicated by the need to separately form the many components (electrodes, flow field, membrane, etc.) by the formation and assembly of individual components from a variety of materials. In the case of microfabricated fuel cells, a suitable support substrate, usually silicon, alumina, glass or other ceramic material which serves only as a passive supporting structure and provides no active function in the operation of the fuel cell, is employed. Such structures suffer from various yield losses due to the complexity of integration and are expensive to realize.